Bytes Converter
Convert between bytes, KiB, MB, GB and bits, in both systems.
Developer Tools
Format, encode and hash without leaving the tab.
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JSON Formatter
Beautify, minify and validate JSON with precise error locations.
Base64 Encoder & Decoder
Convert text to Base64 and back, with full Unicode support.
UUID Generator
Generate cryptographically random version 4 UUIDs in bulk.
README Generator
Fill in the fields and get a complete README.md in Markdown.
Fake Company Generator
Generate believable company names, domains and details for mockups.
Port Number Lookup
Find what runs on a port, with a note on whether it should be exposed.
IBAN Validator
Validate an IBAN's length, country and mod-97 checksum, and generate test ones.
JSON to SQL Insert
Turn an array of JSON records into INSERT statements, with an optional CREATE TABLE.
CSS Formatter
Re-indent a stylesheet, or strip it back to one line.
YAML Validator
Check YAML parses and find the line where the indentation goes wrong.
IPv4 to IPv6 Converter
Convert an IPv4 address into every IPv6 form that carries it, and back.
XPath Tester
Run XPath expressions against your own XML and see every node that matches.
Mock JSON Generator
Describe a shape and get as many rows of matching JSON as you need.
MD5 Generator
Generate an MD5 hash of any text, with a straight answer about when not to.
Hash Generator
Produce SHA-1, SHA-256, SHA-384 and SHA-512 digests of any text.
Bcrypt Generator
Hash a password with bcrypt, or check one against an existing hash.
JSONPath Tester
Run JSONPath expressions against a document and see every match live.
Box Shadow Generator
Build layered box shadows visually, with a live preview.
UUID v5 Generator
Generate deterministic UUIDs from a namespace and a name.
AES Encrypt & Decrypt
Encrypt text with a password using AES-GCM, and decrypt it back.
JWT Decoder
Decode a JWT and read its header, claims and expiry in plain English.
ASCII Table
The full ASCII table with decimal, hex, octal, binary and HTML entities.
XML Formatter
Pretty-print XML with clean indentation, or collapse it back to one line.
JSON Repair
Fix broken JSON: trailing commas, single quotes, unquoted keys and comments.
Slugify for Developers
Turn any text into a safe slug, filename, anchor or branch name.
Bitwise Calculator
AND, OR, XOR, shifts and rotates, at 8 to 64 bits, shown in binary.
Semver Comparator
Compare two semantic versions and test them against a range.
Dockerfile Generator
Generate a production Dockerfile with multi-stage builds and layer caching.
CIDR Range Calculator
Work out a subnet: network, broadcast, host range and usable count.
ASCII Banner Generator
Turn text into a block-letter ASCII banner for a README or a CLI.
HTML Table Generator
Build an accessible HTML table from pasted data or by hand.
JSON Minifier
Strip every optional byte from a JSON document and see what you saved.
Duration Converter
Convert a duration between seconds, ISO 8601, clock time and words.
Test Credit Card Generator
Generate Luhn-valid test card numbers that no processor will ever charge.
HTML Formatter
Re-indent HTML without breaking whitespace-sensitive elements.
ULID Generator
Generate ULIDs — sortable by creation time and case-insensitive.
API Key Generator
Generate prefixed API keys in the format modern providers use.
CRC32 Calculator
Compute a CRC-32 checksum in hex, decimal and signed form.
TOML Formatter
Tidy a TOML file: consistent quoting, ordered tables, keys before headers.
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About these developer tools
A developer utility belt that works offline. Pretty-print and validate JSON, encode or decode Base64 and URLs, generate UUIDs and produce SHA hashes. No installs, no sign-up, and your payloads never leave your machine.